From the State of the Art, actively clocked PFC circuits (Power Factor Control Circuits and/or Power Factor Correction Circuits) with at least one actively clocked switch and the management system and/or control system of PFC circuits of said type by a control unit are already known.
Circuits of said type serve in control gears for light sources, such as, for example, an LED array comprising one or more LEDs, to transform a d.c. voltage or an a.c. voltage supplied to a specific voltage level. At the same time, actively clocked PFC circuits are being used in order to present a consumer with a power factor of almost 1, if an a.c. voltage, such as, for example, a mains a.c. voltage is supplied to the PFC circuit.
In order to achieve this, the actively clocked PFC circuit, in particular the at least one switch of the actively clocked PFC circuit, is managed and/or controlled in such a manner by the control unit that the current consumed precisely like the a.c. voltage comprises a sinusoidal variation in time. As a result, harmonic currents in the supply network can be reduced which would occur in the case of a variation in time, which is not sinusoidal, of the current consumed by the PFC circuit. This means that the control unit is controlling and/or is clocking the at least one switch of the actively clocked PFC circuit in such a way that the current consumed by the PFC circuit is adjusted to a sinusoidal envelope curve in order that the current exhibits a sinusoidal variation in time in accordance with the sinusoidal variation in time of the a.c. voltage with which the PFC circuit is supplied.
There are various known modes of operation in which the control unit can operate a PFC circuit, such as, for example, the continuous current mode (CCM), the discontinuous current mode (DCM) and the borderline mode.
Typical of the borderline mode is the fact that the at least one switch of the actively clocked PFC circuit is switched on when the current through the coil of the actively clocked PFC circuit is dropping to zero amperes (0 A). This has the disadvantage that the zero crossing of the current through the coil must be measured and must be supplied to the control unit. Contrary to this, in discontinuous current mode (DCM), the at least one switch is controlled with a fixed frequency, this means that it is switched on after a fixed period of time and/or after a fixed time span, wherein for each switching cycle a dead time exists during which no current is flowing through the coil.
The State of the Art with respect to actively clocked PFC circuits and a power factor correction with circuits of said type can, for example, be taken from the following publications:                the U.S. Pat. No. 5,777,866,        the US Patent Application US 2009/0141524 A1, as well as        the international Patent Applications WO 2011/009717 A2 and WO 2007/121944 A2.        
PFC circuits form in control gears for light sources such as, for example, LEDs, often only a first converter stage. As a result, often at least one further converter stage for the operation of the light sources is connected to a PFC circuit which is supplied with the output voltage VBUS of the PFC circuit. This at least one converter stage then constitutes a constant current source or a constant voltage source which, in the case of an LED load, generates the corresponding LED current or the corresponding voltage for the operation of the LED load. The at least one converter stage can be an actively clocked current source and/or a linear current source which is controlled by an own control unit.
In order to guarantee an operation of the PFC circuit and of the at least one converter stage adjusted to modified input voltage conditions and/or load conditions, the control units of these two circuits must be coordinated with each other.
Now, it is the objective of the present invention, to provide an intelligent PFC module, which comprises an actively clocked PFC circuit, and an integrated circuit as a control unit, wherein the actively clocked PFC circuit is being operated and/or being controlled by the integrated circuit in discontinuous current mode (DCM). Moreover, it is the objective of the present invention, to provide a system comprising an intelligent PFC module of said type and at least one further converter stage connected to the PFC circuit of the PFC module for the operation of an LED array, with one or more LEDs, wherein the at least one converter stage is likewise controlled by the integrated circuit and/or by the integrated control circuit of the PFC module.
This objective is achieved in accordance with the invention by the features of the independent patent claims. The dependent patent claims develop further the central idea of the invention in a particularly advantageous manner.